MPI_Win_free frees the window object \fIwin\fP and returns a null handle (equal to MPI_WIN_NULL). This collective call is executed by all processes in the group associated with \fIwin\fP. It can be invoked by a process only after it has completed its involvement in RMA communications on window \fIwin\fP, that is, the process has called MPI_Win_fence, or called MPI_Win_unlock to match a previous call to MPI_Win_lock. When the call returns, the window memory can be freed.
Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI::Exception object.
Before the error value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.
